ETIOLOGIC HETEROGENEITY OF NEURAL-TUBE DEFECTS .2. CLUES FROM FAMILY STUDIES

  • 1 January 1982
    • journal article
    • research article
    • Vol. 34  (6) , 980-987
Abstract
Among neural tube defects (NTD) with no known causes, the ones that occur alone (singles) have different epidemiologic characteristics from those that occur in combination with other defects (multiples), suggesting an underlying causal heterogeneity. Family histories were compared for 223 single NTD cases and 66 multiple cases ascertained through the Metropolitan Atlanta Cogenital Defects Program (MACDP) [USA] from 1970-1979. Compared with siblings of multiples, siblings of singles had a higher precurrence rate for NTD (2.0% vs. 0.0%) and for birth defects in general (10.9% vs. 3.0%). Siblings of singles that were born within 2 yr before the birth of the index case had a higher precurrence rate for NTD (8.0% vs. 1.1%) and for major birth defects (2.0% vs. 2.9%) than had those born earlier. NTD are etiologically heterogeneous, depending on the presence of associated defects, and point to important environmental influences in the increased risk for birth defects among siblings of singles. Larger studies are needed to confirm these data and show that single and multiple NTD have different recurrence rates, not only for NTD but also for other birth defects.

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